A solar cell is an energy converter that converts solar energy into electric energy by the photovoltaic effect of semiconductors. So far, the solar energy has become the most important renewable energy source except hydroelectric power. Materials currently used for commercially-available solar cell modules include monocrystalline silicon, polycrystalline silicon, amorphous silicon, cadmium telluride, copper indium gallium selenide and so on, but most of them are high in energy consumption and high in cost.
In recent years, a perovskite solar cell has gained widespread attention. This perovskite solar cell uses an organometallic halide as a light absorbing layer. The preparation of a thin film solar cell from the material has the advantages of simple process, low production cost, high stability and high conversion rate. Since 2009, the photoelectric conversion efficiency of the thin film solar cell has been raised from 3.8% to 22% or above, which is higher than that of the commercially-available crystalline silicon solar cell; and the thin film solar cell has great cost advantages over the commercialized crystalline silicon solar cell.
The core of the existing perovskite solar cell preparation, i.e., the preparation of a perovskite layer, can be accomplished in two ways: a solution-based way and a vapor-based way. Among them, the solution-based way has low requirements for the production environment and equipment and is easy to operate, and the film can be prepared under normal temperature and pressure. However, the uniformity of the formed perovskite thin film is poor, there are too many pinholes in the microstructure of the film, the leakage current is high, the efficiency of the solar cell is seriously affected, and the reproducibility is poor. Therefore, this way is not suitable for large-scale and large-size production. The vapor-based way may overcome these difficulties through more precise control on environment and production process parameters and may realize large-scale production through simple equipment expansion. One method for the vapor-based way involves the preparation of the perovskite layer using methods and equipment similar to those of chemical vapor deposition (CVD). In the prior art, the reactant vapor in the used CVD equipment flows unidirectionally along with carrier gas to the surface at one side of a substrate before being deposited, diffused and reacted, and a baffle is used for obscuration in order to ensure transparency at the other side of the substrate, which reduces the preparation efficiency of the perovskite layer since the baffle side of the substrate is completely unused. More importantly, in the actual production and application of a photovoltaic module, the final cost and production of the module are closely related, i.e., the higher the production is, the lower the cost of the module is.